Suture and method of packaging and sterilizing the same



Aug. 19,1941. w. s. DAVIS ETAL SUTURE AND METHOD OF PACKAGING AND STERILIZING THE SAME Filed July 14, 1959 35 50mm; opal/010M25 Patented Aug. 1 9, 1941 S UTURE AND METHOD OF PACKAGING AND STERILIZING THE SAME Walter-.8. Davis, Los Angeles, Caliifi, and Charles T. Davis, Chicago, Ill., assignors of twenty per cent to Walter W. Pltann, twenty per cent to Arthur Pitann, twenty per cent to Alexander I. Newman, five per cent to Michael M. Newman,

and eight and three-fourths per cent to Haldane Cleminson, all of Chicago, Ill.

Application July 14, 1939, Serial No. 284,388

1 Claim.

The present invention relates to an improved type of sterilized package containing a sterilized suture and the method of packaging said suture and sterilizing the same while within the said package, relating also to the methods employed for introducing into the said package a preserving fluid under aseptic conditions, coupled with means for thereafter hermetically sealing the said package without any possibility of bacterial contamination thereof.

One of the important objects of the present invention is to sterilize, for example, a suture while wound upon a suitable reel or winder contained within a glass tube, the sterilization being accompanied by drying under conditions min imizing the development of undesirable harshness and brittleness in the suture, followed by introduction into the said tube, under aseptic conditions, of asterilized or aseptic preserving fluid such as, for example, alcohol. The process also involves the method used for the introduction of this alcohol by the employment of a partial vacuum and the particular manipulative steps employed for the final sealing of the said glass tube by suitable sealing means. The final product resulting from the operations hereinbelow described is a glass tube provided with means for breaking it at a predetermined place, containing a suture wound upon a suitable reel, which latter is preterably so constructed that it readily falls apart after its removal from the tube, the entire assembly of suture and reel being totally immersed in a fluid such as alcohol, which however does not completely fill the tube, the rest or the space within the tube containing sterile air.

For a better understanding thereof, the present invention and its various features have been illustrated on a sheet of drawings filed concurrently herewith and forming a part of the present specification, in which drawing- Figure 1 is an elevational view on a reduced scale of a package of the type described, plugged temporarily with a sterilized plug of cotton;

Fig. 2 is an elevational view of the completed sterilized suture and package of the present invention;

Figs. 3 and 4 show the two halves of the preferred form of winding reel employed for preventing the suture from becoming tangled or twisted in the tube;

Figs. 5 and 6 are modifications showing other types 01' readily separable winding reels; and

Fig. 7 is a diagrammatic representation of the means employed for sterilizing the package containing the suture and tor introducing into the package or glass tube the sterilized preserving fluid or alcohol.

As is well known in surgery, two different types of sutures are employed by surgeons. The one kind is known as a "nonboilable suture and the other as a "boilable suture. The only real difference between'the two is that the nonboilable suture is preserved in a fluid such as alcohol which still contains a small amount of water, for,

as is well known, ordinary ethyl alcohol of commerce contains about of actual ethyl a1cohol and the rest is water. The completely dry sutures when preserved in such ethyl alcohol will absorb suflicient of the water thereof to keep them flexible so that in a surgical operation they may be manipulated and tied conveniently and quickly by the surgeon. Such suture package or tube is, however, considered nonboilable because it cannot be immersed in boiling water .or steam for the purpose of sterilizing the exterior of the tube by reason of the fact that, due to the presence of moisture, the collagen of the catgut or other such suture material is, under the influence of heat, converted into gelatin and the suture consequently. rendered brittle and weak, and

thereby ruined. The boilable sutures, on the contrary, are preserved in a non-aqueous or nonhydrous fluid; and, by reason of the complete absence of moisture, the sutures withstand heat without deterioration.

The present invention, while of course it can be and is applied to boilable sutures, is described in connection with the preparation of the nonboilable variety simply as a matter of example, for the modification in the process necessary to produce a boilable suture merely involves the substitution of an anhydrous organic liquid, such as toluene or xylene, for alcohol.

It is, of course, well known that sterile sutures in glass containers have been furnished to surgeons for many years past, and no novelty per se is claimed for such a package containing a sterilized suture except when such package is produced by the methods herein disclosed and hereinafter claimed. For a better understanding of the improvements attained by the practice of the present invention, it may be useful to describe at this point some of the prior art methods employed for the packaging of sutures, so that the dlflference between the prior art methods and those of the present invention may be better appreciated.

Thus, under the ordinary methods of producing sutures, the gut string or catgut is coiled and inserted into a glass tube, whereafter this tube with the therein contained suture is dried in an oven, one end of the tube however being left open. Thereafter the sterilization of the suture is effected as a separate and distinct step from the drying operation. In the prior art sterilization process, the tube after drying was removed from the drying oven and was then placed in a sterilizer, which might consist of a heated bath of cumene in which the open tube and gut were submerged. Alternatively, a suitable oven could be employed for sterilization. In any event, the tube and suture were subjected simultaneously to a temperature sufliciently high to kill any microorganism or its spores. The temperatures hitherto employed by various manufacturers of packaged sutures has varied both as to intensity and time, and some of the combinations employed were, for example, 275 F. for five hours, 320 F. for one hour, 300 F. for two hours, etc. The particularly weak feature of such a method of sterilization is that the tube necessarily undergoes the heat treatment with one end completely open, thereby exposing the suture, as well as the interior of the tube after sterilization, to the hazard of accidental contamination or infection. The prevention of such accidental contamination in accordance with the prior art methods therefore depended entirely upon the care and skill with which the operators in the suture-packaging laboratory maintained an aseptic environment about the tube and its contents. Furthermore, even after sterilization it was necessary to introduce into the tube its content of preserving fluid, and the operation of inserting this fluid again provided many possibilities for introduction of bacteria or spores to the sterile suture, thereby completely undoing all the sterilization. The avoidance of such accidental contamination therefore required a rigorously skillful technique. In some of the suture-manufacturing establishments the tubing or preserving fluid was inserted into the tubes containing the sterlized suture by means of a glass pipette or similar laboratory utensil which had been properly sterilized, the operation being effected under a muslin or glass hood in an attempt to provide aseptic conditions. It will be obvious that this, in many cases, fell short of the desired degree of asepsis and therefore provided a constant source of possible infection. In laboratories where the cumene method of sterilization had been employed, the open-ended tube was submerged in a bath of cumene or other anhydrous fluid and then sterilized by heating. The tube, after removal from the liquid, was sometimes immediately plugged with sterile absorbent cotton as a guard against subsequent accidental contamination, whereafter the tube was filled by means of a sterilized hollow or tubular needle, which was pushed through the cotton and through which the proper amount of tubing fluid was inserted by means of a hypodermic or similar syringe. It will immediately be recognized that there again possibilities for contamination were present.

In accordance with the present invention, contamination of the catgut suture and the interior of the tube is completely avoided by the following operative manipulations, which constitute the process features of the present invention. In order to provide a complete picture, we shall now describe the entire set of operations employed in the manufacture of the sutures through to the production of the final, complete and sterile packages or tubes. Some of the steps, such as the tanning of the sutures, are of course well and then preferably partly dried. At this stage,

of course, sterile conditions need not be rigorously observed, although of course laboratory cleanliness is maintained in order to avoid too great contamination of the strands by bacteria. The chromicized and partly' dried suture is then wound upon a small reel made of hydrated cellulose known as vulcanized fiber, the white variety preferably being used, although obviously different colors may be used and may be employed as a means for indicating the type of suture contained in a given package. Inasmuch as the removal of the suture by the surgeon might involve unwinding it from the reel, the reel is preferably made of two separate parts, for example as shown in Fig. 3. It will be noticed that Fig. 3. shows two parts 8 and 9 of a reel, the two parts being in reality identical in shape but placed in such a manner as to be mirror images of each other. The two pieces are then pushed together until the reel 5 is formed as shown, housed in the tubes I of Figs. 1 and 2, respectively. It will be readily appreciated that when the gut is wound upon the reel and the same is inserted into the tube I, the two halves B and 9 cannot come apart, and therefore the reel remains intact. It will be noticed that the tube also has a constricted portion 3 which keeps the reel and the thereon wound suture from sliding freely in the tube. In the indentation 3, after manufacture or before, there is placed a fine etched or engraved line which enables the tube to be snapped in half with assurance that it will break at that point. The reel in its assembled position is also illustrated outside the tube in Fig, 4, where the portion of the reel 9 which lies behind the portion 8 is indicated by dotted lines.

An alternative construction is shown in Fig. 5, in which one-half of the reel I0 is made with a bifurcated end II and the other half I2 is made with a bifurcated end I3, the two pieces being laid on top of each other so that the end I4 of the lowermost reel portion will be kept from sliding onto the bifurcated end II by the suture wound thereon.

As a further alternative, a construction such as that shown in Fig. 6 may be employed, in which the reel I5 is made with two bifurcated ends and centrally perforated at I6 so that it may be readily broken apart after removing the reel and the thereon wound suture from the tube I.

Irrespective as to what type of reel is employed, the suture is wound thereon and is then inserted into the bottom of the tube I as shown in Fig. 1.

- No liquid is put into the tube at this stage, but

that a large number of tubes may be treated at the same time. being supported in suitable racks made either of metal or heatproof plastic ma-' terial, porcelain or the like. The tube I having been placed in the interior of the oven 22, the lid 2| is secured thereto and tightly clamped down. The sterilizing chamber 20 is housed entirely within a suitable heated oven 22 which may be of the electrically heated type. In any event, the oven 22 is capable of heating the sterilizing chamber 20 and its content to the desired sterilizing temperature. The sterilizing chamber 20, it will be seen, is provided with a pipe 23 provided with a valve 24 and a further extension 25 leading to a suitable vacuum-creating device (not shown). On the opposite side of the sterilizing chamber 20 there is a similar pipe 28, provided with a valve 21, and a pipe 28, the end of which leads to a bacteria-proof air filter 23. The bottom of the sterilizing chamber 20 is also provided with a tube 30, in which. there is a valve 3|, and a bacteria-proof fllter 32 from which leads a pipe 33 to a tank 34 containing the tubing solution or alcohol. The tank 34 is provided with a pipe 35 and valve 36 so that a vacuum may be created therein, while a further tube 31 provided with a valve 38 leads to another bacteria-proof air filter 39.

The operation is continued as follows: The heat, having been turned on in the oven 22. will gradually raise the temperature of the sterilizing vessel 20 to the desired point; but while the tem perature is rising a vacuum is created within the chamber 20 by opening the valve 24 and connecting the pipe 25 with a suitable vacuum-creating mechanism or pump. Therefore the tubes, the therein contained sutures, the cotton plugs, and the reels will gradually be relieved of all their contained moisture under the combined influence of the heat and the vacuum. At the same time. as the temperature finally reaches the sterilizing point and is maintained there for the their spores so that at the end of this period the entire contents of the chamber 20 will be completely sterile. The temperature attained at the innermost portion of the chamber 20 is constantly measured and preferably recorded by means of the thermometer bulb 40 which is connected either electrically or otherwise through the tube 4| with the recording dial 42 so that a constant record of the temperature can be kept. Preferably this record is a permanent bne and is preserved by the manufacturer for reference purposes. After the sterilization has been effected, the valve 24 is closed and the valve 21 opened in order to break the vacuum, the air being taken from the interior of the oven 22 through the bacteria-proof air filter 29. A particular advantage in drawing the air from the interior of the oven is that such air is also sterile to begin with, and the, bacteria-proof filter is an added precaution. It is preferred to break the vacuum to a point where the pressure within the chamber is atmospheric. The valve 21 is then closed, and thereafter the valve 3| is,opened, thus establishing connection with the tank 34 containing sterile alcohol. There is a sufficient amount of fluid in the tank 34, and this is drawn into the chamber 20 by again creating a suflicient vacuum therein to draw the fluid through the sterile filter 32 into the sterilizing chamber 20 so that it will rise therein until the tubes, including the cotton plugs, are completely submerged, with the level of alcohol sufllciently high above the cotton plugs to permit the next step of the operation, which is as follows:

The valve 3| is closed, thus shutting off the connection between the tank 34 and chamber 20. More air is then exhausted from the chamber 20 to a predetermined degre of vacuum, the purpose being to draw out some of the air contained within the tubes preferably about half the air therein contained. Actually, what happens is that the pressure within the tubes is reduced to the required degree. Thereafter the valve 24 is closed and the valve 21. opened very slightly so as to again admit air into the chamber 20 through the bacteria-proof filter 29. As the air within the tubes contracts as a result of the again increased pressure, the alcohol or other tubing fluid which stands above the top of the tubes will gradually filter into the tubes through the wad or plug of sterile cotton 6. It is preferred to do this operation slowlyto avoid the plugs being pushed into the tubes. When equilibrium with the atmosphere has been established, it will be found that the tubes have been filled to a point, say, slightly above the indentation 3 so that the tubes at that stage will present the appearance of the tube shown in Fig. 1. Thereafter, with the valve 21 still open, the valve 3| is opened and the valve 36 on tank 34 is opened so as to create suction which will draw the alcohol from the chamber 20 into the tank 34. It will be noticed that the tank 34 is provided with a valve 38, pipe 31 and filter 39, and it will be understood that the valve 38 is closed during this stage of the process. Previously, however, when letting the liquid flow from the tank 34 to the chamber 20, the vacuum valve 36 will have been closed and the air valve 38 opened, as otherwise the alcohol would not flow from the tank 34 to the chamber 20.

In the present stage of the operation all of the alcohol is drawn from the chamber 2|) back into the tank 34, whereafter the valve 3| is closed, thus placing the interior of the chamber 20, through the pipe 26 and valve 21, in equilibrium with the atmosphere within the oven. The chamber 20 is also opened, by removing the lid 2|, whereafter the basket containing the tubes of sterile sutures is removed and set on a laboratory table. The tubes are then, without removing the plugs, placed in a suitable rack, and the alcohol adhering and absorbed in the cotton 6 is set afire and allowed to burn off. The burning of this alcohol has a triple effect; it assures the resterilization of the plug and the destruction of any bacteria which may have fallen upon it during the operation of removing the tubes from the chamber 20, while at the same time it serves to preheat the upper end of the tube i so that it can then be subjected to the heat-sealing means which are employed for sealing the tubes. This operation may be done by hand, but it is preferred to accomplish it on a sealing machine, which contains means for rotating the tubes in an upright position in the path of a series of impinging flames which uniformly heat the tube at a point interrnediate the indentation 3 and the cotton plug 6 until it is soft enough to be clamped shut by a suitable instrumentality which fuses the glass together,

producing a hermetic seal. These operations are, of course, well known in the technique of sealing ampules and also in the process of sealing electric light bulbs, radio tubes, and the like.

It will be seen from the description hereinabove that the contents of the tubes are entirely protected from the time sterilization in the oven is completed until the mechanical glass seal is produced. The method of introducing the alcohol is believed to be entirely unique and is of course carried out at a temperature below the boiling point of alcohol. In other words, the tubes are allowed to cool in the chamber 20 until the temperature has been reached which permits the introduction of the alcohol without allowing it to reach its boiling point.

In using the suture, the surgeon need merely break the tube at the indentation 3 and remove the suture by means of a sterile forceps, grasping either the suture or the bifurcated end of the reel, whereafter it may be allowed to fall upon a sterilized towel and be threaded to the surgeon's needle under the usual aseptic conditions of the operating room. Inasmuch as no human hands touch either the sutures or the interior of the tubes after they havebeen sterilized, and as the sterile alcohol is introduced through the sterile cotton plugs, it will be appreciated that the possibilities for contamination are substantially zero. The present method therefore presents a very great advance in the method of handling and. sterilizing packaged sutures, as contrasted with the inherently dangerous methods of the prior art.

It is also within the contemplation of the invention to effect the plugging of the tubes by means of cotton plugs 6 in an automatic device, which however forms no part of the present invention, and the plugs may be placed either mechanically or by hand.

It has been found that a vacuum of about from 18 to 22 inches is sufficiently high to exhaust enough air from the tubes so that they will fill with alcohol or other tubing fluid to the desired level. Of course, if the tubes are laid down in shipment or use, the alcohol will naturally run to the other end, but this makes no difference because there is always an equilibrium between the alcohol and its vapor in the tubes, so that even if the tubes are laid down the sutures will not lose whatever moisture they may have absorbed from the alcohol.

It will be readily understood that if the nonboilable sutures are to be made, toluene or xylene may be substituted for the alcohol and the tubes filled with either of these or equivalent liquid in place of the alcohol, the manipulations being otherwise absolutely identical.

If desired, other articles used for surgical purposes may be packaged in accordance with the method hereinbefore described.

Many variations in the foregoing detailed description will readily be apparent to those skilled in the art. Thus the drying step may be carried out under ordinary atmospheric pressures or even under increased pressures if desired, instead of under partial vacuum. Likewise, in the filling operation, instead of creating a partial vacuum V and thereafter increasing the pressure, simple gravity filling or the use of positive pressure may in some cases be preferred, although under ordinary circumstances vacuum filling will be found more satisfactory. Again, it is not essential that the plugs be made of cotton, as any other suitable porous plugging material may be used. Furthermore, the sterilization step may if desired be carried out while the tube is filled with the aseptic liquid. In this case, of course, the aseptic fluid should have a boiling point such that vaporization thereof does not take place under the pressure and temperature conditions prevailing during the sterilization step. Thus it may be desirable in some cases to effect sterilization under superatmospheric pressures in order to prevent the vaporization of the aseptic liquid in the tubes. Many other variations will be apparent to those skilled in the art, and these are to be included within the ambit of the appended claim.

We claim:

The process of producing a sterilized and packaged suture which comprises placing the suture in an open-ended tube at a point spaced from the open end of said tube; closing the tube against ingress of microorganisms with a porous plug adapted to pass a preserving liquid; subjecting the tube and its contents to heat at a sterilizing temperature in a hermetically closed sterilizing chamber for a predetermined period of time, and subjecting said tube to a vacuum concurrently with the heating for removing the moisture from the tube and its contents; introducing suture preserving liquid into said sterilizing chamber to a depth to submerge said tube in said liquid; causing a reduction of the pressure in said sterilizing chamber by application of a predetermined degree of vacuum to remove a predetermined amount of air from said tube, then reestablishing atmospheric pressure in said sterilizing chamber, while said tube is submerged, to cause the preserving liquid to filter through the plug into said tube to a predetermined depth; removing the excess of preserving liquid from said sterilizing chamber; drying off the preserving liquid from said plug; and then without removal of the porous plug sealing said tube at a point between the level of said liquid in said tube and the said plug, whereby, bacteriologically, the process forms a closed system.

WALTER S. DAVIS. CHARLES T. DAVIS. 

